General Knowledge - Basic General Knowledge - Discussion

Alum is hydrated potassium aluminium sulfate (potassium alum) with the formula KAl(SO4)2.12H2O. More widely, alums are double sulphate salts, with the formula AM(SO4)2.12H2O, Industrial uses.

Potassium alum is the common alum of commerce, although soda alum, ferric alum, and ammonium alum are manufactured.

Alum has been used at least since Roman times for purification of drinking water and industrial process water. Between 30 and 40 ppm of alum for household wastewater, often more for industrial wastewater, is added to the water so that the negatively charged colloidal particles clump together into "flocs", which then float to the top of the liquid, settle to the bottom of the liquid, or can be more easily filtered from the liquid, prior to further filtration and disinfection of the water.

What is alum ?

Coagulation is the process in which impurity is removed by adding certain chemical.

What is coagulation?

To coagulate, means to form semi-solid lumps.